The present invention relates generally to positioning systems used for controlling the rotation of a shaft or other member through a defined angular increment, and more particularly to an indexing assembly therefor which may be hydraulically or pneumatically powered and which is less complicated than prior devices but which is robust and which provides for precise and reliable angular positioning.
A variety of mechanical, electromechanical, fluid power, and electronic rotary indexing mechanisms are known and used in a host of commercial, industrial, mobile, and military applications for providing incremental rotation of a shaft or the like through a selected angular increment. Mechanical devices include pawl and ratchet assemblies in which a first pawl rotates a ratchet and a second pawl maintains the rotated ratchet at its end-of-movement position, as well as detent mechanisms in which a resiliently-biased detent member engages the rotated member at selected detent positions. Electro-mechanical devices typically employ solenoids or other electromechanical actuators that have been adapted to drive mechanical mechanisms. Fluid power devices may utilize hydraulic motors or a pump or other source of fluid pressure in conjunction with an arrangement of hydraulic or pneumatic cylinders. Electronic devices generally involve the use drive motors, typically of the stepper variety, in conjunction with position sensors to control of the magnitude of displacement of the rotary increment and to signal the stop position of the rotated member. Devices illustrative of the foregoing are shown, for example, in U.S. Pat. Nos. 6,279,722; 6,240,807; 5,974,941; 5,860,333; 5,735,514; 5,501,123; 5,187,847; 5,136,896; 5,073,514; 5,064,044; 5,044,055; 5,033,367; 4,991,463; 4,890,514; 4,890,514; 4,887,345; 4,884,474; 4,852,428; 4,644,825; 4,622,145; 4,442,726; 4,134,305; 3,961,780; 3,960,475; 3,945,505; 3,927,574; 3,889,572; 3,888,140; 3,888,140; 3,797,333; 3,785,223; 3,020,998; and 2,339,986.
The above-described rotary indexing devices heretofore known in the art have proved satisfactory for a diversity of uses. However, each may offer specific advantages and disadvantages in any particular application. For example, in certain applications, electrical or hydraulic motors may require excess power input and can constitute a considerable expense relative to those applications. Also, in applications requiring high speeds, concerns may exist regarding inertia and the ability to stop the device or otherwise to achieve accurate positioning. Electric motors, moreover, generally are not specified for use in explosive atmospheres.
The aforementioned devices have constituted the state of the art with respect to rotary indexing assemblies. It is believed, however, that further improvements in such assemblies continue to be desired by industry and, particularly, by the military for aerospace applications such as for use as a carousel actuator in the delivering of ordinance from aircraft and other platforms. In this regard, a preferred assembly would be economical to manufacture, but additionally would be reliable, lightweight, and compact so as to be easily integrated into a variety of system designs.